Thousands of protesters gathered in Moscow to mark the first anniversary of an anti-Kremlin demonstration last year that ended in violence and with the arrest of hundreds of demonstrators.

Monday's rally in Moscow's Bolotnaya Square marked last year's protest, which fell the day before Vladimir Putin was sworn in for a third presidential term.

Participants in Monday's rally called on authorities to release some 26 people facing charges related to last year's demonstration.

Opposition leader Alexei Navalny urged demonstrators to "throw Putin out of the Kremlin."

Former Russian Deputy Prime Minister and opposition leader Boris Nemtsov said the protesters' demands remain the same as the year before: freedom for political prisoners, end to persecution and presidential term limits.

"Our demands have not changed. Our demands are what they have always been: liberation of political prisoners, an end to political persecution and intimidation of the people. I mean the political trials against (Alexei) Navalny and (Sergei) Udaltsov. We demand a limitation to the powers of the president, who wants to rule (this country) for his entire life."

Critics say that Mr. Putin's first year back as President has been marked by new laws restricting freedom of assembly and independent non-governmental organizations.

An estimated 15,000 people attended the rally, less than half of the 50,000 estimated to have turned out one year ago.